Electrical apparatus



Oct. 30, 1956 M. c. HARROLD ELECTRICAL APPARATUS Filed May 25, 1954 United States Patent ce ELECTRICAL APPARATUS Marshall C. Harrold, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware This invention relates to electrical apparatus and more particularly to snap-acting switches.

It is an object of my invention to provide a simple snapaction device which may conveniently be used to operate switch contacts.

It is particularly an object of my invention to provide such a device in a very simple inexpensive form which is durable and has long life.

These and other objects are attained in the form shown which includes as its principal element a thin spring metal member in substantially the shape of a hollow four-cornered figure with the two diagonally opposite corner portions connected by a tension spring and with the contacts actuated by the other of the two diagonally opposite corner portions.

Further objects and advantages of the present invention will be apparent from the following description, reference being hadto the accompanying drawings-wherein a preferred form of the invention is clearly shown.

In the drawing:

Figure 1 is a top view of a control embodying one form of my invention;

Figure 2 is a sectional view taken substantially along the line 22 of Figure 1;

Figure 3 is a sectional view taken substantially along the line 3-3 of Figure 2;

Figure 4 is a sectional view taken substantially along the line 4-4 of Figures 1 and 3;

Figures 5 is a sectional view similar to Figure 2 showing the control in the open circuit position;

Figure 6 is a perspective view of the snap action element;

Figure 7 is a perspective view of a modified form of snap-action element;

Figure 8 is a small diagrammatic front view showing the use of a compression spring applied to the spring member (shown bowed upwardly) in place of the tension spring; and

Figure 9 is a small diagrammatic side view of the compression spring arrangement shown in Figure 8 with the spring member bowed downwardly Referring now to the drawing and more particularly to Figures 1 and 2 there is shown a switch casing 20 of electrical insulating material. This casing is shown as being octangular in shape but it may be made if desired either rectangular or circular. Extending through the bottom of this casing 20 are a set of spaced contacts 22 and 24 (see Figure 4) having their upper ends extending up into the interior compartment 26 of the casing and having their lower ends extending beneath the casing 20 and provided with suitable binding screws 28.

As shown in Figure 2, in the closed circuit position these contacts 22 and 24 are adapted to be bridged by a thin spring metal member 30 which is preferably in the shape of a hollow four-sided diamond shaped figure with rounded corners. Two diagonally opposite corners are provided with the switch contacts 32 and 34 which are 2,769,048 Patented Oct. 30, 1956 adapted to rest upon the top of the terminals 22 and 24. These contacts are held firmly in contact with the terminals 22 and 24 by the tension coil spring 36 which connects the apertures 38 and 40 in the other diagonally opposite corners of the spring metal member 30.

These other diagonally opposite corners containing the apertures 38 and 40 are lodged within the notches 42 and 44 provided in the actuating yoke 46. This yoke 46 is normally pressed upwardly against the adjustable stop screws 48 and 50 by the compression type coil springs 52 and 54. In the arrangement shown, this normally insures that the contacts will be held in closed position. The contacts 32 and 34 may be moved to open position by an actuating pin 56 provided with a head 58. This head 58 may be manually pushed in for actuation or it may be operated by any form of fluid motor such as a bellows or diaphragm. Also instead of this, the spring metal member 30 may be made of bimetal so that the effective temperature will cause the contacts 32 and 34 to snap to and form open and closed position in accordance with changes in temperature. Directly above the contacts 32 and 34 the casing 20 is provided with the adjustable stop screws 60 and 62. These limit the opening movement of the spring metal member 30. Where it is desired to have a normally open switch the contact terminals 22 and 24 may be interchanged with the stop screws 60 and 62.

If desired either the stop screw 48 or the stop screw 50 may be adjusted until the adjacent end of the yoke member 46 is prevented from movement and the entire actuation is then obtained through the movement of the other end as a lever freely movable as a lever about its other end as a virtual pivot. the movement of the pin 56 is multiplied by the lever action of the yoke 46 to make the control device more sensitive.

It will be seen that this device is capable of a large number of variations and consequently a large variety of applications. It is simple, durable and inexpensive. In Figure 7, for example, a modified form of thin spring metal member is shown also in the shape of a hollow four-sided diamond shaped figure. It differs from the member 30 by having notches 138 and on two opposite corners receiving the hooked ends of the tension coil spring 136, thus avoiding the necessity of making the holes 38 and 40 as in the member 30. Contacts 132 and 134 may be provided at the other corners.

In Figures 8 and 9, a fiat U-shaped spring 236 has its upwardly extending end portions 238 provided with horizontal slots which receive the projections 240 on the diametrically opposite corners of the thin spring metal member 230 which is otherwise identical to the spring metal member 30. The end portions 238 fit in the notches 42 and 44 replacing the member 30 and spring 36 in Figures 1 to 5 with sufficient lateral clearance to allow the bowing of the spring 236. The spring 236 places a compression load upon the member 230 with substantially the same eflect as the spring 36 has upon the member 30. The member 230 includes contacts 232 and 234 corresponding to contacts 32 and 34. The operation is substantially the same as shown in Figures 1 to 5.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted as may come within the scope of the claims which follow.

What is claimed is as follows:

1. A control including a set of normally stationary switch contacts spaced apart and electrically insulated from each other, stop means spaced from each of said switch contacts, a thin spring metal member with a large central opening substantially in the shape of a hollow four cornered figure with one set of diagonally opposite In this particular arrangement corners located between said switch :contacts and said stop means, spring means connecting the other set of diagonally opposite corners acting in a direction to urge said other set toward each other to arch said member alonga line extending directly across said one set of diagonally opposite corners, and actuating means for moving atileast one of the two corner portions 'to which the spring means is connected in ,a direction transverse to said member to arch said member to the opposite curvature.

2. A control including a set of normally stationary switch contacts spaced apart .and electrically insulated from each other, stop means spaced from each of said switch contacts, a thin spring metal member with a'large central opening substantially in the shape of a hollow four corneredfigure with one set of diagonally opposite corners located between said switch contacts and said stop means, spring means connecting the other set of diagonally.opposite corners acting in a direction to urge said other set toward .each other to arch said member'along a line extending directlyacross said one set of diagonally opposite corners, and actuating means for moving at least one of the two corner portions to which the spring means is connectedlina direction transverse to said member to arch said member to the opposite curvature, and means for limiting the movement of the other corner portion to which the spring means is connected.

3. A control including a set of normally stationary switch contacts spaced apart and electrically insulated from each other, stop means spaced from each of said switch contacts, a thin spring metal member with a large central opening substantially in the shape of a hollow four cornered figure with one set of diagonally opposite corners locatedtbetween said switch contacts andsaid stop means, spring means connecting the other set of diagonally opposite corners acting in a direction to urge said other set toward each other to arch said member along a line ex- 7 tending directly across saidvone set ofdlagonallyopposite corners, and actuating means for moving at least one of the two corner portions to which the spring means is connected in a direction transverse to said member to arch said member to the opposite curvature, said thin member being of temperature =responsive bimetal.

4. A control including a set of normally stationary switch contacts spaced apart and electrically insulated from each other, vstop means Spaced from eachof said switch contacts, a thin spring metal member :lsubstantially in the shape of a hollow four sided figure having -a :four sided central opening vhaving its sides substantially ,parallel to the four sides of said member with one set of'the diagonally opposite portions-connecting thelsides being located between said switch contacts and said stop means, spring means connecting the other diagonally opposite portions connecting the sides acting inta direction to urge said other portions toward each other to arch said member across the diagonal connecting sa'idone set of diagonally opposite portions, and actuating means for moving at least one of the diagonally opposite portions to which the spring means is connected ,in a direction transverse to the thin member to arch said member to the opposite curvature.

References Cited in the file of this patent UNITED STATES PATENTS 1;784,450 Klahn .Dec. 9, 1930 1,907,869 Raney May '9, 1933 2,166,238 Bavis July 118, 1939 2,166,239 JDavis ;Iuly :18, 1939 2,204,792 Davis June 1118, 19.40 2,266,537 Elmer Dec. .16, 1941 2,345,240 .Cox.. vMar. 28, 1944 2,545,264 Davis .Mar. :13, 1951 

